1. Field of the Invention
The present invention relates to amplifying arrangements in general, and more particularly to radio frequency amplifying arrangements operative over a relatively wide gain range.
2. Description of the Related Art
There are already known various arrangements for amplifying electrical signals, including arrangements that have been designed for use or are particularly suited to be used for amplifying alternating current signals at frequencies as high as in the :radio frequency (RF) range. While such previously known amplifying arrangements have been found to satisfy most if not all performance criteria put on them, a perennially problematical area has been the gain range within which an amplifying arrangement of a reasonably simple and commensurately inexpensive construction is able to accomplish the required level of amplification without incurring unacceptable signal distortion.
With the increasing demand for services involving the utilization of the broadcast spectrum, which demand has become even more pronounced since the advent of such relatively recent telecommunications service offerings as radio paging, cellular telephony and other voice and/or data broadcasting techniques, it has become apparent that approaches that may have worked to satisfaction in the past are no longer suitable for such uses. This is so, if for no other reason, then because the equipment used by the ultimate user or subscriber, besides operating at relatively low transmitted signal power levels, is often being used in a mobile manner, that is, the subscriber transmitter and/or receiver equipment accompanies the subscriber as he or she travels from place to place, frequently while the equipment is being used. This, in turn, means that the power of the transmitted signal as received at any particular receiving location or station varies within a relatively wide range and often quite abruptly, be it because the respective subscriber transmitter or receiver has moved behind, or emerged from behind, a signal attenuating obstruction, because of changing distance between the transmitter and receiver, as a result of changing atmospheric or other relevant environmental conditions. or for other similar reasons.